Self loading utility knife

Abstract

A self-loading utility knife including an elongate handle having an internal chamber defining an axis and at one end is flat aperture for the passage of an active blade. The flat aperture defines a cutting plane extending through said handle along the axis. A blade-holder is slidably mounted in the chamber for movements in directions along the axis and is adapted to secure a single active blade for movement through the aperture when the blade holder is in the extended position. A blade-holder release button is coupled to the blade holder and is slidingly movable relative to the handle to move blade holder between retracted and extended positions. The handle has a blade compartment which is open to the chamber and can receive a stack of spare blades when a cover to the compartment is opened and blades can be shifted transversely relative to the axis into the chamber. The blade holder is provided with a recess having a depth no greater than the thickness of one blade to allow at least a portion of a single blade to be received in a retaining relationship within the recess to cause an end-most blade in the stack to be received within said recess to follow the movements of the blade holder. A spring biases the blades in the blade compartment inwardly in the direction of the blade holder. A blade releasing disc on the blade holder selectively locks a blade to the blade holder when the blade holder is in the extended position. The blade holder only receives a single blade within the recess. A belt clip s provided on the compartment cover.

We claim as follows: 
     
       1. A self-loading utility knife comprising: an elongate handle having an internal chamber generally defining an axis and an upper edge extending along a predetermined length of said axis, one end of said handle being a remote end formed with a generally flat aperture suitable for the passage of an active blade with clearance and a notch in said upper edge proximate to said flat aperture and the other end of said handle being a proximate end, said generally flat aperture defining a cutting plane extending through said handle along said axis; a blade-holder slidably mounted within said chamber for movements in directions along said axis between an extended position and a retracted position, said blade holder being adapted to secure a single active blade for movement through said aperture when said blade holder is in said extended position; a blade-holder release button generally arranged along said cutting plane and coupled to said blade holder, said release button having an outer portion that is located exteriorly of said handle, said release button being slidingly movable relative to said handle along said predetermined length to cause said blade holder to move to selected positions between said retracted position and said extended position, said handle being provided to one side of said cutting plane with a blade compartment open to said chamber and arranged at a predetermined position along said axis between said remote and proximate ends and generally dimensioned and configured in the shape of said active blade for receiving a plurality of stacked spare blades arranged generally parallel to said cutting plane so that the spare blades in said blade compartment are shifted transversely relative to said axis into said chamber, said blade holder being provided with a recess having a depth no greater than the thickness of one blade and shaped to correspond to at least a portion of a blade closest to said proximate end to allow at least a portion of a single blade to be received in a retaining relationship within said recess to cause the blade received within said recess to follow the movements of said blade holder; an access cover on said handle for selectively opening and closing said blade compartment for insertion or removal of spare blades; biasing means provided on said access cover for biasing blades within said blade compartment inwardly in the direction of said blade holder when said access cover is in its closed position; locking means for selectively maintaining said access cover in closed or open positions; and a blade releasing means on said blade holder wherein when said blade holder is in the extended position the blade releasing means is located in said notch above a portion of the upper edge defined by the notch such that the blade releasing means will release a blade from the blade holder when a user's thumb draws the blade releasing means rearwardly towards the proximate end of the handle, and when the blade holder is in the retracted position the blade releasing means is located entirely below the portion of the upper edge not defined by the notch, said blade holder only receiving a single blade within said recess, said blade holder being movable to a position juxtaposed to said blade compartment when said blade holder is in a predetermined retracted position in registry with said recess, whereby after an active blade has been removed through said flat aperture said biasing means are caused to automatically move a spare blade along a direction transversely to said axis into said recess for movement to an operative position through said flat aperture when said blade holder is moved to said extended position and movement of said blade holder and release of a blade in said extended position can be implemented through a one handed operation. 
     
     
       2. A self-loading utility knife as defined in  claim 1 , wherein said elongate handle is formed of a pair of clamshells one to each side of said cutting plane. 
     
     
       3. A self-loading utility knife as defined in  claim 1 , wherein said blade holder release button is positioned along the top of said handle when the utility knife is normally held during use, whereby said blade holder release button can be engaged and actuated by the thumb of the user. 
     
     
       4. A self-loading utility knife as defined in  claim 1 , wherein said blade release means comprises a disc mounted on said blade holder including an engaging tab receivable in a notch of a blade, said disc being resiliently biased to normally move said engaging tab into said notch for locking the blade to said blade holder. 
     
     
       5. A self-loading utility knife as defined in  claim 1 , wherein said handle is provided with an inwardly curved region at said remote end to expose said blade releasing means only when said blade holder is in said extended position. 
     
     
       6. A self-loading utility knife as defined in  claim 1 , further comprising blade holder locking means for selectively locking the position of said blade holder in a plurality of positions between said remote and proximate ends of said handle. 
     
     
       7. A self-loading utility knife as defined in  claim 6 , wherein said blade holder locking means comprises mating elongate recesses on opposing surfaces of said chamber facing said blade holder, a plurality of upwardly extending pairs of notches associated with each of said elongate recesses, said blade holder release button being provided with a transverse bar dimensioned to be received within said elongate recesses and within said pairs of notches, a spring being provided to normally urge said transverse bar to move upwardly in the direction of said notches, whereby said transverse bar is generally guided through said elongate recesses when said blade holder slides between said extended and retracted positions and locks said blade holder at a position corresponding to said notches into which said transverse bar is received and said blade holder can be unlocked only when said blade release button is depressed manually against the action of the spring to remove said transverse bar from said notches and moved into said elongate recesses. 
     
     
       8. A self-loading utility knife as defined in  claim 1 , further comprising a belt clip secured to said access cover. 
     
     
       9. A self-loading utility knife as defined in  claim 1 , further comprising a blade holder safety lock for locking said blade holder to said handle independently of actuation of said blade holder release button. 
     
     
       10. A self-loading utility knife as defined in  claim 1 , wherein said axis is a curved axis conforming to the shape of said handle. 
     
     
       11. A self-loading utility knife as defined in  claim 1 , wherein said access cover is generally elongate and is hinged to said handle at one end of said cover and said locking means comprises a spring biased retainer for selectively engaging a tab on said cover. 
     
     
       12. A self-loading utility knife as defined in  claim 1 , wherein said biasing means comprises a leaf spring. 
     
     
       13. A self-loading utility knife as defined in  claim 1 , further comprising protuberance means within said blade compartment dimensioned to be received within notches on said stack of spare blades to maintain said blades aligned with said recess as said blades are successively moved closer to said blade holder to assure proper registry with said recess and reliable engagement of a blade transferred from said blade compartment onto said blade holder by being received within said recess.